I. Field Of The Invention
The present invention relates to a grinding machine for grinding a workpiece, comprising a machine frame, a bearing device provided on the machine frame and movable along guides, in which bearing device a cup-shaped grinding wheel is borne, drivable in a rotating way about a grinding wheel axis and electrically insulated, which wheel is constructed of electrically conductive material and has a first grinding region with an annular abrasive surface and second grinding regions with abrasive surfaces in the shape of the lateral area, in each case consisting of an electrically conductive bonding material and abrasive grit embedded therein, which grinding wheel is electrically connected to a generator, means for holding the workpiece to be ground, a device for conditioning the grinding wheel with at least one movable electrode, which is likewise connected to the generator, and means for supply of a cooling lubricant to the electrode and to the workpiece.
II. Description Of Related Art
Grinding machines of this type are known. With such grinding machines, indexable inserts, for example, are able to be ground, which procedure has to take place with high precision, for which purpose the grinding wheel must also be kept in optimal condition with respect to precision and sharpness. To ensure this quality of the grinding wheel, the wheel must be prepared and conditioned accordingly. Essentially three steps are hereby carried out, i.e. profile dressing, sharpening and cleaning of the grinding wheel.
The profile dressing operation, by which the grinding wheel is brought into the desired shape, is usually carried out for each new grinding wheel. A profile dressing operation is also carried out when the grinding wheel has been in use for a longer period of time. In a known way, such a profile dressing operation is executed with a silicon carbide wheel that can be brought into contact with the grinding wheel in the grinding machine or with which the grinding wheel in the grinding machine can be brought into contact. Besides grinding wheel material, also silicon carbide from the dressing wheel is thereby also removed. This silicon carbide ends up in the cooling lubricant loop, and must be removed from the coolant lubricant medium as quickly as possible since this material is very aggressive. To do this, suitable and costly apparatus are necessary.
During the step of sharpening a grinding wheel, the bonding material of the abrasive surface is reduced to improve the height of the grinding grains projecting over the bonding material. It is known to carry out the step of sharpening of the grinding wheel for metal-bonded grinding wheels by means of electrochemical methods in which an electrochemical stripping of the conductive bonding material of the abrasive surface of the grinding wheel takes place by means of an electrode and an applied electrolyte. The stripped material must then be filtered, in a complex and time-consuming way, out of the electrolytic medium, acting as cooling lubricant, for which purpose expensive devices are needed.
The cleaning of the grinding wheel, by which the swarf which has been created by the grinding operation and which has accumulated in the irregularities of the abrasive surface, is removed, can be carried out in a known way with a white corundum wheel. It can also be carried out, however, using the previously described electrochemical method, whereby the aforementioned drawbacks arise with both methods.